1. Field of the Invention
The present invention relates generally to information and storage systems and networks.
2. Description of Related Art
According to recent trends, there is a concept referred to as a “storage grid,” in which a multiple distributed computing resources are put into operation to act as a single entity. Such storage grids are becoming more widely used in the storage industry. As one form of a storage grid, a configuration may be constructed in which a plurality of storage control units are arranged together and act as a single storage system. In such a configuration, multiple storage control units are connected to each other via an inter-unit network. The multiple storage control units exchange management information and data through the inter-unit network to enable them to function as a single storage system. However, a drawback to such a storage grid arrangement can occur when the inter-unit network itself is used to process input/output (I/O) requests from host computers. In particular, the processing performance of the I/O requests can be degraded when the inter-unit network has to be used to process an I/O request in comparison with the processing performance for an I/O request that is completed solely within one of the storage control units without using the inter-unit network.
Related art includes U.S. Pat. No. 6,779,083 B2, to Ito et al., entitled “Security for Logical Unit in Storage Subsystem”, and U.S. patent application Ser. No. 11/826,717, to J. HARA et al., filed Jul. 18, 2007, entitled “Method and Apparatus for Managing Virtual Ports on Storage Systems”, the entire disclosures of which are incorporated herein by reference. Related art also includes the Fibre Channel Standard and corresponding specification documents, such as are available from the InterNational Committee for Information Technology Standards (INCITS) Technical Committee T11 (e.g., t11.org). Especially, for example, documents relating to FC-FS (Fibre Channel Framing and Signaling), FC-DA (Fibre Channel Device Attach), FC-LS (Fibre Channel Link Services), FC-GS (Fibre Channel Generic Services), and FC-PH (Fibre Channel Physical and Signaling Interface) are related to this invention. For example, “Fibre Channel Framing and Signaling-3 (FC-FS-3), Project T11/1861-D Rev 0.20”, Published by the American National Standards Institute, Inc. Jun. 29, 2007, the disclosure of which is incorporated herein by reference, describes the framing and signaling requirements for Fibre Channel links.